ESL makes a beep sound when the user selects an enabled object; it makes a boop sound when the user misses all objects, selects a disabled object, or selects an enabled object for which there is no active response. It makes a third sound (approximately between a beep and a boop) when the user tries to select a disabled Windows object. The only exceptions are when a user selects a dialog box or dialog region for which no response exists, in which case no sound is made.

You can control the sound frequency (in Hertz) of the beep and the boop by setting values for the following commands in the CONFIG.ESL file. The higher the value, the higher the frequency.

BEEPFREQ Sound frequency for correct selections (beep). Initially, this command is set to a default value of 1250 in the CONFIG.ESL file.

BOOPFREQ        Sound frequency for incorrect selections (boop). Initially, this command is set to a default value of 250 in the CONFIG.ESL file.

You cannot change the frequency of the Windows sound.

In a windowed program, you should probably disable ESL's beeps and boops, to conform to Windows. Specify the -nb option on the command line to disable the beeps and boops.